THE 
LONDON, EDINBURGH, ann DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[FIFTH SERIES.] 
MARCH 1885. 
XX. On the Seat of the Electromotive Forces in the Voltaic Cell. 
By Professor Ottver J. Lopasr, D.Sc. 
To the Editors of the Philosophical Magazine and Journal. 
GENTLEMEN, 
HE accompanying tract is an expansion of a paper drawn 
up as the opening of a discussion on Contact Electricity 
by Section A of the British Association at the Montreal 
Meeting. It isin five portions or chapters. The first of 
these | printed this month] is mainly historical; in the second 
and third portions theoretical views are considered, and my own 
are given at some length in accordance with the kind advice 
of Sir W. Thomson ; the two remaining chapters are occu- 
pied with cognate thermoelectric phenomena, with the theory 
of the simple voltaic cell, which singularly enough is pretty 
complicated and very litte understood, and with a discussion 
on the size of atoms. Although the paper is being printed in 
the annual volume of the Association, it has been suggested 
that a further publication of it might be useful in order that 
Physicists may have a better and more leisurely opportunity of 
contributing to the discussion of a matter which must have 
eccupied the attention of every one more or less, which branches 
out into several interesting and important developments, and 
which, as a matter of controversy, has remained singularly 
long unsettled. I will therefore ask you to find room for it 
in your Journal, in the hope that the discussion may be there 
conveniently continued and properly closed. 
I am, Gentlemen, 
University College, Liverpool, Your obedient servant, 
December 1884. OuiveR J. Lopes. 
Phil. Mag. 8. 5. Vol. 19. No. 118. March 1885. M 
